The plot is kinda self-explanatory by reading the ingame text, but here's a quick plot from Giant Bomb:
"The game starts the player in a car that has been recently crashed--and is about to explode. After regaining his senses and slowly realize that he in danger, the unnamed protagonist manages to escape the exploding car. After recovering from that shock, the hero realizes that his sibling is missing (a younger brother in the original Mac version, or an older sister in the NES port). After looking around, the player will notice an ominous mansion several steps away."
So, you need to save your brother, which would be kinda hard without a walkthrough. I don't think I ever would have completed this game without some help (I'm not too bright tho ;)).
*Pauses I make are for you to read the texts (I do it at the same time and add +2ish secs before continuing).*
Being lazy, I followed some random video walkthrough on YouTube. I found out later that he skipped a lot. Like, how do we know the spells I keep using? And the code for the safe? At the end I show quickly where these hints are, and those are actually among the first steps you should do, but in this video they ended up being the last. So.... not done in a good order, which is why I explain some of them here in case you wonder :)
27:34 - Reading the scroll here gives you the "Specan Heafod Abraxas" spell-words.
28:08 - This scroll gives you the safe code. Gold (#79), silver (#47), mercury (#80). Thus the combination is 79-47-80.
There were probably more hints to find, but didn't wanna spend more time trying to find them.
You don't have to operate items on stuff, you can also drag them from the inventory, but as I've been using the operate way in Deja Vu 1-2 (probably Shadowgate too), I kept doing it here as well. But did use drag once at 25:36 just for the hell of it. I know, it's faster, but still :)
Loads of ways you can die, here's a couple you might be wondering about:
* You can enter the sarcophagus at 17:19, what happens is someone closes it, you run out of air and die. So didn't do it of course, but at least showed this place.
* You can go down below the altar at 21:41 if you try to go a 5th time (I only did 4). What happens is you see a big, black scary spider, and you of course die :)
Yeah, was a lazy run, so not showing all rooms or deaths. Like Deja Vu 1-2, I show one death at the end, just so we see the general game over part.
I used the WHDLoad version and it didn't include the certificate in the end, so saved my gave to a floppy disk, ran the floppy version and recorded it from there instead. Had to click to be able to type, even though you could already see the input thingy.
If you see the mouse teleport from one location to another, it's not bad editing, the cursor just moves like shit for some reason in these type of games when using WHDLoad. Running from floppy is OK. Have to have the mouse speed set to 30 (default is 100) and it makes it a bit more manageable. Not playing games like this too often so haven't really looked into a fix. No settings I've tried in WinUAE seem makes it better, so it's either WHDLoad, or something in my plain WB install that causes it. Oh well :)
By request, a special NES music version: https://youtu.be/NDq82ytwWTY